Title : A Study of the Accuracy of Visual Planimetric Pointings to Photographic Edges with Different Characteristics.

Descriptive Note : Final rept. 28 Jun 69-15 Sep 71,

Corporate Author : WASHINGTON UNIV SEATTLE DEPT OF CIVIL ENGINEERING

Personal Author(s) : Colcord,J. E. ; Lund,Kenneth ; Hussain,Musthaq

Report Date : SEP 1971

Pagination or Media Count : 160

Abstract : The basic variations and parameters tested and discussed concern Mean Pointing Values in Relation to the Physical Edge, Precision of Pointing with various Edges, and Mach Band Measurements. Most observers show greater consistency with a sharp edge target of high contrast. While the position obtained in a tangent pointing task varies with observer by almost 30 seconds of arc, most tend to a systematic bias with pointing to the bright field most common. Further observer variation is apparently psycho-physiologically dependent and varies significantly with time. The influence of color is rather insignificant as again individual observers had large differences, however, a slightly better correlation and more pleasant working conditions were felt to occur in the yellow-green region of the spectrum. (Author)